Benzene, C15-16-alkyl derivs.

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP study published in peer-reviewed journal.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Version / remarks:

EPA/TSCA

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Alkylate 215

IUPAC Name:

Alkylate 215

Constituent 2

Reference substance name:

Benzene, C10-16-alkyl derivs.

EC Number:

272-008-4

EC Name:

Benzene, C10-16-alkyl derivs.

Cas Number:

68648-87-3

IUPAC Name:

tridecylbenzene

Details on test material:

- Composition of test material, percentage of components: <1% C9, 16% C10, 43% C11, 40% C12, 1% C13, <1% C14; avg C11.26
- Analytical purity: 98.5

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Housing: wire mesh cages
- Diet (e.g. ad libitum): Ralson Purina commercial laboratory feed, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 65-79
- Humidity (%): 17-76
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: 7 nights, if female was still not pregnant, she was moved to another male for an additional 7 nights, and then to a third male if needed
- Proof of pregnancy: vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged (how): individually

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

daily

Frequency of treatment:

F0: Treatment was started 10 weeks before mating. For males, dosing continued for 2 weeks after mating (total of 105 days). For females, dosing continued through lactation for a total of 127 treatment days.

F1: The F1 generation was treated similarly to the F0 generation, but were exposed beginning 11 weeks pre-mating.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 5, 50 and 500 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

30 animals of each sex per dose

Control animals:

yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly


BODY WEIGHT: Yes
- Time schedule for examinations: males - weekly, females - weekly before mating, days 0, 7, 14, and 20 of gestation, and days 0, 4, 14, and 21 of lactation


FOOD CONSUMPTION: weekly

Litter observations:

STANDARDISATION OF LITTERS
F1 pups were selected for mating at weaning, at least one pup per litter was selected for the adult F1 generation


PARAMETERS EXAMINED
The following parameters were examined in F1 and F2 offspring:
number and sex of pups on days 0, 4, 7, 14, and 21 of lactation, postnatal mortality and presence of gross anomalies daily, weights on days 0, 4, 7, 14, and 21 of lactation

GROSS EXAMINATION OF DEAD PUPS:
yes

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals 2 weeks after mating.
- Maternal animals: All surviving animals at weaning.


GROSS NECROPSY
- Gross necropsy consisted of examination for gross lesions


HISTOPATHOLOGY / ORGAN WEIGHTS
pituitary glands, testes and epididymides, prostate and seminal vesicles, vagina, uterus, ovaries, and gross lesions

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring not selected as parental animals and all F2 offspring were sacrificed at weaning.
- These animals were subjected to postmortem examinations similar to parental animals above.

Reproductive indices:

mating index, pregnancy rate, fertility index

Offspring viability indices:

pup survival

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Reproductive function / performance (P0)

Reproductive performance:

effects observed, treatment-related

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No mortality attributed to treatment was observed.


BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Mean body weights of high-dose-group (500 mg/kg bw/d) males were significantly and consistently reduced {12 = 0.01) in the FO (since premating week); mean body weights of high-dose females were significantly decreased in the FO generation since the 9th week of premating until the first week of lactation (p = 0.05); body weight reduction was significant on day 20 of gestation in both generations (p = 0.01


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Mating, pregnancy and fertility rates were not influenced.


GROSS PATHOLOGY (PARENTAL ANIMALS)
No gross postmortem findings.

HISTOPATHOLOGY (PARENTAL ANIMALS)
No histopathological findings.

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw/day

Basis for effect level:

other: Maternal and paternal general toxicity was reduced weight gain in the high dose group. Reduced litter size in the high dose group.

Results: F1 generation

General toxicity (F1)

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Details on results (F1)

VIABILITY (OFFSPRING)
Litter size: Fl and F2 : significant decrease at 500 mg/kg bw/d (p = 0.05 and 0.01 respectively);
pup viability index at birth: Fl: significant decrease at 50 and 500 mg/kg bd/d (p = 0.05) F2: significant decrease at 500 mg/kg bw/d (p = 0.05), since effects at 50 mg/kg bw/d was only noted in a single generation, these effects were not considered biologically significant; survival of pups at day 4 was significantly decreased at 500 mg/kg bw/d in the Fl and F2 litters; survival of pups at day 21 (related to day 4) was significantly decreased only in the F2 litter at 50 mg/kg bw/d (p = 0.05), since effects at 50 mg/kg bw/d was only noted in a single generation, these effects were not considered biologically significant

BODY WEIGHT (OFFSPRING)
mean pup weight:
Fl litters; significant reduction at 50 and 500 mg/kg bw/d at day 7 and only at 500 mg/kg bw/d at day 14 and 21 (p = 0.05), since the reduction in the 50 mg/kg bw/d group was only noted at day 7 and only in the F1 generation, this effect was not considered biologically significant
F2 litters: significant reduction at 500 mg/kg bw/d at day 14 and 21 (p = 0.05).


OTHER FINDINGS (OFFSPRING)
In the high-dose-group, gestation length was significantly increased for the F2 litter interval (22.4 d compared to 22.0 in controls).

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

50 mg/kg bw/day

Basis for effect level:

other: Reduced survival and weight gain in high dose group. Sporadic occurrences at mid dose level.

Results: F2 generation

Effect levels (F2)

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

50 mg/kg bw/day

Basis for effect level:

other: Reduced survival and weight gain in the high dose group. Sporadic occurrences at mid dose level.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

Litter Size and Pup Survival Indices

Dose (mg/kg/day)	Litter size (mean)	Pup viability index at birth (%)	Pup survival days 0-4 (%)	Pup survival days 0-4 (%)^1	Pup survival days 4-21 (%)
F1 litters
0	12.7	99.1	93.8		95.7
5	12.8	98.0	93.4		91.0
50	13.1	95.4	92.3		84.2
500	10.0	95.4	85.0		94.7
F2 litters
0	11.3	98.6	80.2	93.5	98.1
5	11.6	98.2	87.3	94.4	97.1
50	13.1	97.3	89.5	92.3	89.1
500	7.0	89.0	84.1	85.9	97.3

¹Excludes data for litters in which all pups died during the Day 0-3 interval.

Mean Pup Weights (g)

Dose (mg/kg/day)	Day 0	Day 4- Precull	Day 4- Postcull	Day 7	Day 14	Day 21
F1 litters
0	6.0	8.4	8.4	13.2	27.0	42.7
5	5.9	8.1	8.1	12.9	27.3	42.1
50	5.8	7.5	7.6	11.4	25.1	39.6
500	5.8	8.1	8.1	11.4	23.5	37.7
F2 litters
0	5.8	8.1	8.3	13.9	27.0	40.5
5	5.8	8.5	8.5	14.4	26.9	42.0
50	6.0	8.1	8.1	13.4	25.3	39.5
500	5.8	8.1	8.1	12.1	22.3	34.6

Applicant's summary and conclusion

Conclusions:

The NOEL for the maternal and paternal generation was 50 mg/kg bw/day and for the offspring generations.

Executive summary:

In cases where no data were available on the target substance, Benzene, C15 -16 -alkyl derivs., data were read across from a structurally related material (the test substance).

This study examined the effects of exposure to the test substance on reproduction. Groups of 30 female and 30 male rats were exposed to concentrations of 0, 5, 50 and 500 mg/kg day of test substance by oral gavage beginning ten weeks before mating. Animals were then mated. The resulting generation was also exposed to the test substance and mated. Exposure continued through the mating period, and in females through the gestation and lactational periods. All animals were sacrificed and necropsied after exposure. Pups not used for mating were sacrificed at weaning. During the study, animals were observed for clinical signs, mortality, and body weight. Pups were examined for viability and body weight gain. Reproductive indices were also calculated. The NOAEL for parental toxicity was 50 mg/kg/day and the LOAEL was 500 mg/kg/day based on reduced weight gain and litter size in the high dose group. The NOAEL for offspring was 50 mg/kg/day based on reduced body weight gain and survival in the high and mid-dose groups. The LOAEL for offspring was 50 mg/kg/day.